| 1. |
- Birdsong, Björn K., et al.
(författare)
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Flexible and fire-retardant silica/cellulose aerogel using bacterial cellulose nanofibrils as template material
- 2024
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409.
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Tidskriftsartikel (refereegranskat)abstract
- This study explores the possibility of using various silsesquioxane precursors such as (3-aminopropyl) triethoxysilane (APTES), methyltrimethoxysilane (MTMS), and tetraethyl orthosilicate (TEOS) to produce silsesquioxane-bacterial cellulose nanofibre (bCNF) aerogels. Each precursor allowed to customize the aerogel properties, leading to unique properties suitable for various applications requiring lightweight insulative materials. When utilizing APTES as the silsesquioxane precursor, an aerogel capable of over 90% recovery after compression was formed, making them suitable for flexible applications. When MTMS was used as the precursor, the aerogel retained some compression recovery (80%) but had the added property of superhydrophobicity with a contact angle over 160° due to the presence of CH3 functional groups, enabling water-repellence. Finally, TEOS allowed for excellent thermal insulative properties with a low Peak Heat Release Rate (PHRR), making it a promising candidate for fire-resistant applications. The customization of these aerogel materials was attributed to a combination of the chemical composition of the silsesquioxane precursors and the morphology of the coated bacterial cellulose nanofibres (bCNF), such as CH3 groups found in MTMS enabled for superhydrophobicity. Differences in morphology, such as uniform and smooth silsesquioxane coatings when using APTES or a “pearl-necklace” morphology using TEOS, enabled either compression recovery and flexibility or low thermal conduction. This investigation of silsesquioxane-bCNF provides a good understanding of the importance of the choice of precursor effect on insulating aerogel properties.
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| 2. |
- Capezza, Antonio Jose, et al.
(författare)
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Acylation of agricultural protein biomass yields biodegradable superabsorbent plastics
- 2021
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Ingår i: Communications Chemistry. - : Springer Nature. - 2399-3669. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- Superabsorbent polymers (SAP) are a central component of hygiene and medical products requiring high liquid swelling, but these SAP are commonly derived from petroleum resources. Here, we show that sustainable and biodegradable SAP can be produced by acylation of the agricultural potato protein side-stream (PPC) with a non-toxic dianhydride (EDTAD). Treatment of the PPC yields a material with a water swelling capacity of ca. 2400%, which is ten times greater than the untreated PPC. Acylation was also performed on waste potato fruit juice (PFJ), i.e. before the industrial treatment to precipitate the PPC. The use of PFJ for the acylation implies a saving of 320 000 tons as CO2 in greenhouse gas emissions per year by avoiding the industrial drying of the PFJ to obtain the PPC. The acylated PPC shows biodegradation and resistance to mould growth. The possibilities to produce a biodegradable SAP from the PPC allows for future fabrication of environment-friendly and disposable daily-care products, e.g. diapers and sanitary pads.
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| 3. |
- Das, Oisik, et al.
(författare)
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The Effect of Carbon Black on the Properties of Plasticised Wheat Gluten Biopolymer
- 2020
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Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 25:10
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Tidskriftsartikel (refereegranskat)abstract
- Wheat gluten biopolymers generally become excessively rigid when processed without plasticisers, while the use of plasticisers, on the other hand, can deteriorate their mechanical properties. As such, this study investigated the effect of carbon black (CB) as a filler into glycerol-plasticised gluten to prepare gluten/CB biocomposites in order to eliminate the aforementioned drawback. Thus, biocomposites were manufactured using compression moulding followed by the determination of their mechanical, morphological, and chemical properties. The filler content of 4 wt% was found to be optimal for achieving increased tensile strength by 24%, and tensile modulus by 268% along with the toughness retention based on energy at break when compared with those of glycerol-plasticised gluten. When reaching the filler content up to 6 wt%, the tensile properties were found to be worsened, which can be ascribed to excessive agglomeration of carbon black at the high content levels within gluten matrices. Based on infrared spectroscopy, the results demonstrate an increased amount of β-sheets, suggesting the formation of more aggregated protein networks induced by increasing the filler contents. However, the addition of fillers did not improve fire and water resistance in such bionanocomposites owing to the high blend ratio of plasticiser to gluten.
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| 4. |
- Mäki, Rikard, et al.
(författare)
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Wet clutch transmission fluid for AWD differentials : influence of lubricant additives on friction characteristics
- 2006
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Ingår i: Automotive and industrial lubrication. - Ostfildern : Techn. Akad. Esslingen. - 3924813620 ; , s. 35-
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Konferensbidrag (refereegranskat)abstract
- A study on the influence of base oils on friction properties was carried out. The effects of additive interactions must be considered but were hard to predict. This was most notable with EP additives that were hard to combine with other additives without compromising the anti-shudder properties of the clutch. The developed fluid showed that it is feasible to combine anti-shudder properties and hypoid gear lubrication abilities in one fluid. Good anti-shudder properties were realized despite high concentrations of EP additives. This is an abstract of a paper presented at the 15th International Colloquium Tribology-Automotive and Industrial Lubrication (Ostfildern, Germany 1/17-19/2006).
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| 5. |
- Olsson, Jimmy, et al.
(författare)
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Flow and heat transfer inside an autoclave
- 2012
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Ingår i: Proceedings of the 11th International Conference on Flow Processing in Composite Materials.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This work, that involves both experiments and numerical simulations, concerns autoclave molding. An autoclave is basically a pressure vessel, where the entrapped and often highly compressed gas is heated and circulated in order to heat the components that have been placed inside the vessel. In the autoclaveprocess, the desirable state would be that an even and optimal temperature existed in the whole part that is manufactured. Unfortunately, this is not always the case. All in all we need to get a better understanding of the flow inside an autoclave and the convective heat transfer from the heated gas to the composite components. In this work we have therefore investigated the flow behavior by performing qualitative measurements with particle image velocimetry inside an autoclave. The concept is to dope the gas within the autoclave with smoke and illuminate the smoke with a thin sheet of laser light. Captured images of the moving smoke are then cross correlated to give velocity fields. We have also investigated the heat transfer to the tool by measuring the temperature at multiple locations during heating. The obtained velocity field is used to produce inlet condition for the simulations, performed with Computational Fluid Dynamics, which subsequently are compared with the experimentally obtained tool temperature. The simulation technique may then be used to optimize both the tools, and the actual location of the tools inside the autoclave in order to improve quality and reduce costs.
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| 6. |
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| 7. |
- Ramnemark, Anna, et al.
(författare)
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Fractures after stroke
- 1998
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 8:1, s. 92-95
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Tidskriftsartikel (refereegranskat)abstract
- Fractures are a serious complication after stroke. Among patients with femoral neck fractures, a large subgroup have had a previous stroke. This study aimed to investigate the incidence of fractures after stroke. Included in the study were 1139 patients consecutively admitted for acute stroke. Fractures occurring from stroke onset until the end of the study or death were registered retrospectively. Hip fracture incidence was compared with corresponding rates from the general population. Patients were followed up for a total of 4132 patient-years (median 2.9 years). There were 154 fractures in 120 patients and median time between the onset of stroke and the first fracture was 24 months. Women had significantly more fractures than men (chi 2 = 15.6; p < 0.001). In patients with paresis most of the fractures affected the paretic side (chi 2 = 22.5; p < 0.001) and 84% of the fractures were caused by falls. Hip fracture was the most frequent fracture and the incidence was 2-4 times higher in stroke patients compared with the reference population. Fractures are thus a common complication after stroke. They are usually caused by falls and affect the paretic side. It is necessary to focus on the prevention of post-stroke fractures, including the prevention of both falls and osteoporosis.
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| 8. |
- Ramnemark, Anna, et al.
(författare)
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Hemiosteoporosis after severe stroke, independent of changes in body composition and weight
- 1999
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Ingår i: Stroke. - 0039-2499 .- 1524-4628. ; 30:4, s. 755-760
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Fractures are a serious complication after stroke, and the risk of hip fractures among stroke patients is increased 2 to 4 times versus a reference population. Fractures after stroke are probably caused by the development of hemiosteoporosis and the high incidence of accidental falls. The aim of this study was to investigate the development of hemiosteoporosis in relation to other changes in body composition during the first year after severe stroke. METHODS: The study included 24 patients with extensive paresis after stroke. Bone mineral content (BMC) and fat and lean mass were assessed 1, 4, 7, and 12 months after stroke onset by a dual-energy x-ray absorptiometer. RESULTS: The loss of total body BMC was significant during the first year after stroke (-1.6%; P<0.05), but there were no significant changes in total lean or fat mass. At inclusion, there were no significant differences between sides in lean or fat mass or BMC, but during follow-up, BMC of the affected side decreased significantly compared with the same side at inclusion (-7.5%; P<0.01). Side differences in fat mass became significant between legs (9.3%; P<0.001) and whole sides (4. 8%; P<0.01). There were only minor side changes in lean mass. Loss of BMC was independent of weight changes. CONCLUSIONS: During the first year after severe stroke, patients developed pronounced hemiosteoporosis. This was not associated with general changes in lean or fat mass. The development of hemiosteoporosis was independent of weight changes after stroke.
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| 9. |
- Shanmugam, V., et al.
(författare)
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Potential natural polymer-based nanofibres for the development of facemasks in countering viral outbreaks
- 2021
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Ingår i: Journal of Applied Polymer Science. - : Wiley. - 0021-8995 .- 1097-4628. ; 138:27
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Tidskriftsartikel (refereegranskat)abstract
- The global coronavirus disease 2019 (COVID-19) pandemic has rapidly increased the demand for facemasks as a measure to reduce the rapid spread of the pathogen. Throughout the pandemic, some countries such as Italy had a monthly demand of ca. 90 million facemasks. Domestic mask manufacturers are capable of manufacturing 8 million masks each week, although the demand was 40 million per week during March 2020. This dramatic increase has contributed to a spike in the generation of facemask waste. Facemasks are often manufactured with synthetic materials that are non-biodegradable, and their increased usage and improper disposal are raising environmental concerns. Consequently, there is a strong interest for developing biodegradable facemasks made with for example, renewable nanofibres. A range of natural polymer-based nanofibres has been studied for their potential to be used in air filter applications. This review article examines potential natural polymer-based nanofibres along with their filtration and antimicrobial capabilities for developing biodegradable facemask that will promote a cleaner production.
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| 10. |
- Westerberg, Lars-Göran, et al.
(författare)
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Transport of bubbles during compression in a non-Newtonian fluid
- 2009
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Ingår i: Proceedings of ITP2009. ; , s. 10:11-10:22
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Konferensbidrag (refereegranskat)abstract
- Bubble transport is of importance in many applications for non-Newtonian fluids, such as in composite materials manufacturing where residual bubbles may impair electrical properties, surface appearance and the mechanical properties of the manufactured products. In this study, a model experiment is performed where a non-Newtonian fluid(grease) with bubbles is compressed between two plates whereas the motion of the bubbles is tracked and evaluated using Particle Image Velocimetry. The bubble motion is furthermore analytically modeled and coupled to the experimental results.
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